Synthesis and crystal structure of new ternary chalcogenides of group IV metals: K2ZrS4, Rb2ZrS4, and Rb2HfS4

The new ternary one-dimensional chain compounds K2ZrS4, Rb2ZrS4 and Rb2HfS4 were prepared at 350 degrees C by reacting A(2)S(3) and S with elemental M (A = K, Rb; M = Zr, Hf). They are isostructural, crystallizing in the orth orhombic space group Pbca with Z = 8. The M atoms are in a distorted octahe dral environment of four S anions and one S-2(2-) Unit. The structure consi sts of infinite anionic chains comprised of edge-sharing MS6 octahedra runn ing parallel to the [001] direction separated by the alkali metal cations. The composition of the chain may be formulated as (1)(infinity)[MS4/2(S-2)( 2-)]. The two crystallographically independent alkali cations are in eight- and ninefold coordination of S atoms.